Abstract
We commend Iwasa and Nakashima 1 for their brilliant work on dedifferentiated liposarcoma (DDL). In particular, we really appreciated the differentiations the authors assessed between high-grade (HDDL) and low-grade DDL (LDDL), as well as conventional and comingling types of DDL (where the transition from well-differentiated liposarcoma (WDL) to DDL is abrupt in the former and intermingled in the latter). 1 Furthermore, since LDDL proved to have metastatic capability, we concur with them on the concern of using mitotic count as one of the criteria for dedifferentiation, whereas advocate for retroperitoneal localization as a prognostically unfavorable feature of DDL.
Recently, we had to deal with a 69-year-old man affected by a very rare form of DDL, that is, DDL with osteosarcomatous component (ODDL) occurring in the left retroperitoneum. A curative excision of the neoplasm was conducted along with en bloc resection of the greater omentum, spleen, left colon, left adrenal gland, and kidney. The patient did well after the intervention and was scheduled for adjuvant radiochemotherapy with epirubicin and ifosfamide; nevertheless, at 4-month follow-up he developed multiple supracentimetric intra- and retroperitoneal metastases.
Only 17 cases of ODDL are reported in the world medical literature. Of these, 13 occurred in the retroperitoneum. 2 Retroperitoneal ODDL seems to have a predilection for male patients (8 men, 3 women, undeclared gender in 2 instances) ranging in age from 40 to 61 years; of interest, our patient aged 69 years is the oldest to be affected by retroperitoneal ODDL. Ten patients (77%) were Asian (9 from Japan and 1 from South Korea), whereas only 3 patients were Occidental (2 from the United States and 1 from England); hence, our patient is the second to be recorded in Europe and the first from Italy. The tumor size data were available for 8 cases (range = 7-40 cm craniocaudally), whereas the retroperitoneal side was revealed only in 5 instances (2 lesions were right-sided, 2 were left-sided whereas 1 occupied the entire retroperitoneum). Our patient suffered from a 19 cm × 16 cm left-sided retroperitoneal ODDL. Eleven patients underwent surgical treatment, and a percutaneous biopsy of the lesion was conducted with diagnostic intention for two patients with widespread disease. Macroscopically, ODDL commonly appears as uni- or multinodular fatty mass with inner well-defined bony component. Histologically, it is composed of WDL intermingled with osteosarcomatous foci; the interface between the 2 components may be gradual, abrupt, or less frequently, mosaic. 3 The most common pattern was that of a high-grade osteosarcomatous dedifferentiation (6 cases), followed by 3 low-grade cases, whereas in the remaining 4 cases this information was unreported. High-grade osteosarcoma was found also in our patient.
The longest follow-up reported for a patient previously operated for ODDL and free from disease (only 2 cases) is of 7 years and 11 months; besides these, 1 patient died from cancer, 4 cases developed local recurrence and distant metastases, and in 5 cases this topic was not clearly described. Concerning the prognostic significance, the anatomic location seems to be the most important factor for DDL, with the retroperitoneal compartment imparting the worst behavior; on the contrary, the tumor size, expression of MDM2 and CDK4, and histological grade have led to heterogeneous results. 3 In summary, DDL with osteosarcomatous dedifferentiation represents a very rare and complex form of DDL; the information about its main features come from very few case reports and are extrapolated with difficulty from larger series on DDL. Hence, more dedicated reports are required to better assess the anatomopathobiological features of this disease.